You may not know Luis von Ahn by name, but if you're online, you've almost certainly encountered his work. Luis invented CAPTCHA and reCAPTCHA -- those squiggly words and letters you often have to type into web forms to prove that you're a human being.
Today, Luis launches his next big project: Duolingo.
It's a website that aims to translate the entire web into every major world language, using volunteers. Nora interviewed Luis about Duolingo, and why he enjoys working on such large-scale crowdsourcing projects. An edited version of this interview will air on Spark 164, but right now, you can hear the full, uncut interview below, or download the MP3. [runs 19:59]